Hermetically sealed optical fibers

Abstract

A hermetically coated optical fiber is produced by contacting a hot fiber with an organic material such as acetylene. The heat of the fiber causes decomposition and results in a hermetic, carbonaceous coating. This coating is essentially impermeable to both water and hydrogen.

We claim: 
     
       1. A process for producing a coated optical fiber comprising the steps of drawing a fiber from a heated glass body and contacting said fiber with a gas to induce the formation of a coating on said fiber characterized in that said gas comprises a carbonaceous composition, and said contact occurs when said fiber has a temperature sufficiently high to induce a reaction at the surface of said fiber that results in the formation of an adherent carbon coating comprising a crosslinked carbon network and is sufficiently low to avoid the formation of a diamond-like coating. 
     
     
       2. The process of claim 1 wherein said gas comprises an alkynyl. 
     
     
       3. The process of claim 2 wherein said alkynyl comprises acetylene. 
     
     
       4. The process of claim 3 wherein said gas includes a chlorine containing composition. 
     
     
       5. The process of claim 4 wherein said chlorine containing composition comprises a gas chosen from the group consisting of trichloroethylene and chlorine. 
     
     
       6. The process of claim 5 wherein said coated fiber is subjected to a heat treatment. 
     
     
       7. The process of claim 1 wherein said fiber undergoes said contact sequentially, first with a composition comprising a getterer containing gas and said carbonaceous composition and then with a second carbonaceous composition in the absence of said getterer. 
     
     
       8. The process of claim 7 wherein said carbonaceous composition comprises acetylene. 
     
     
       9. The process of claim 7 wherein said getterer comprises a chlorine containing composition. 
     
     
       10. The process of claim 9 wherein said chlorine containing composition comprises trichloroethylene. 
     
     
       11. The process of claim 7 wherein said second carbonaceous composition comprises acetylene. 
     
     
       12. The process of claim 11 wherein said carbonaceous composition comprises acetylene. 
     
     
       13. The process of claim 1 wherein said carbon coating is overcoated. 
     
     
       14. The process of claim 1 wherein said gas includes an entity chosen from the group consisting of chlorine, bromine, and fluorine. 
     
     
       15. The process of claim 1 wherein said fiber contains a getterer for hydrogen or water. 
     
     
       16. The process of claim 1 wherein said glass body comprises a fiber preform. 
     
     
       17. The process of claim 1 wherein said temperature is in the range 700 to 900 degrees C. 
     
     
       18. The process of claim 1 wherein said gas comprises benzene. 
     
     
       19. The process of claim 1 wherein said gas includes a member of the group consisting of chlorine, iodine, fluorine and carbon tetrachloride. 
     
     
       20. The product formed by the process of claim 1. 
     
     
       21. A process for producing a coated optical fiber comprising the steps of drawing a fiber from a heated glass body and contacting said fiber with a gas to induce formation of an hermetic coating characterized in that a getterer is introduced to remove hydrogen or water trapped by said coating. 
     
     
       22. The process of claim 21 wherein said getterer is in said fiber. 
     
     
       23. The process of claim 21 wherein said getterer is introduced in said gas. 
     
     
       24. The process of claim 23 wherein said getterer comprises a chlorine containing compound. 
     
     
       25. The process of claim 24 wherein said chlorine containing compound comprises a gas chosen from the group consisting of trichloroethylene and chlorine. 
     
     
       26. A process for producing a structure comprising a coated optical fiber said process comprising the step of drawing a fiber including a core and a cladding from a heated glass body and coating said fiber characterized in that a getterer for hydrogen or water is introduced into the periphery of said cladding. 
     
     
       27. The process of claim 26 wherein said coating is formed by subjecting said heated fiber to a gas at a temperature sufficient to induce formation of a non-diamond-like crosslinked carbon network. 
     
     
       28. A coated fiber comprising a glass fiber capable of guiding electromagnetic radiation and a coating characterized in that said coating is non-diamond-like, comprises a crosslinked carbon network and has an hermeticity such that the loss measured at 1.24 μm in 1 atm. of hydrogen and at the use temperature does not increase more than 0.05 dB/km in a time period shorter than 1/140 of the desired use period and such that the static fatigue, n, value is greater than 70. 
     
     
       29. The coated fiber of claim 28 wherein said time period is shorter than 1/45 the desired use period.